Q about dyno numbers..
11-28-2002, 01:33 AM
#1
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Q about dyno numbers..
Hi!
I've found a nice 928GT that I might buy, I've been a 928-fan for to long to not own one of these supercars. I always take a look at 928's for sale in my region and have over three years only found one that was 100% right, one almost perfect (for me) cars and far to many that wasn't worth the time looking at them...
This time I might go for it...
While surfing the net I looked at Deveks dyno charts of a stock and non-stock 928GT found <a href="http://www.devek.net/index.php?page=nfo_dynoroom" target="_blank">here.</a>
The max dyno result on the stock car is 308,6 hp.
I've read about driveline loss of around 12-17% for the 928 and wonder if this figure only is true for the autos?
If I divide 308,6 with 85 and multiply it with 100 to get the flywheel hp the result is 363 hp which seems a bit high for a stock car rated to 330 hp and a lot more then a stock GTS...
If the flywheel hp is 330 hp and wheel hp is 308,6 then there would only be a driveline loss of 7,5%. Is it the dyno that is giving high numbers or is it Porsche that give low? Combination?
Anyone who knows the dynoed rwhp of a stock manual 928 GTS?
I've found a nice 928GT that I might buy, I've been a 928-fan for to long to not own one of these supercars. I always take a look at 928's for sale in my region and have over three years only found one that was 100% right, one almost perfect (for me) cars and far to many that wasn't worth the time looking at them...
This time I might go for it...
While surfing the net I looked at Deveks dyno charts of a stock and non-stock 928GT found <a href="http://www.devek.net/index.php?page=nfo_dynoroom" target="_blank">here.</a>
The max dyno result on the stock car is 308,6 hp.
I've read about driveline loss of around 12-17% for the 928 and wonder if this figure only is true for the autos?
If I divide 308,6 with 85 and multiply it with 100 to get the flywheel hp the result is 363 hp which seems a bit high for a stock car rated to 330 hp and a lot more then a stock GTS...
If the flywheel hp is 330 hp and wheel hp is 308,6 then there would only be a driveline loss of 7,5%. Is it the dyno that is giving high numbers or is it Porsche that give low? Combination?
Anyone who knows the dynoed rwhp of a stock manual 928 GTS?
11-28-2002, 10:41 AM
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Remember, Porsche is conservative with their numbers. Also, things like atmospheric temperature and pressure play a big role in the amount of power an engine makes.
Also keep in mind that every dyno is a bit different. One may give a lower or higher number than the next.
I say if you like the car and it drives well on the road, then go get it.
I would still like to find a dyno here in Cincinati, but I don't know of any.
Also keep in mind that every dyno is a bit different. One may give a lower or higher number than the next.
I say if you like the car and it drives well on the road, then go get it.
I would still like to find a dyno here in Cincinati, but I don't know of any.
11-30-2002, 05:09 PM
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Hi Anders, I can see that you are located in Sweden, as me. I belive that 308 hp at rear wheels i exceptional good but something like 290 is probably more like it. The GT have about the same hp as the GTS but less torque. I belive that the GT is was underrated when the factory said 330 hp.
I have driven a 5 gear GTS, you can feel that it has more torque but less top end compared to the GT. The GT is simply more fun above 4000 rpm <img src="graemlins/jumper.gif" border="0" alt="[jumper]" /> . It is quite easy to hit the revlimiter on the GT by mistake.
Lycka till med köpet!
I have driven a 5 gear GTS, you can feel that it has more torque but less top end compared to the GT. The GT is simply more fun above 4000 rpm <img src="graemlins/jumper.gif" border="0" alt="[jumper]" /> . It is quite easy to hit the revlimiter on the GT by mistake.
Lycka till med köpet!
12-01-2002, 08:23 AM
#5
I have dynoed my car on a couple of dynos and spoke to others who have done the same in Australia, not just 928s either, the dyno figures we get are much lower than the US numbers, The US numbers are very optimistic, the point being the GT's figures you mentioned.
My car which is a perfectly tuned 1984 euro s dynoed at 132 kw, at the wheels and is an auto (4 speed) I then improved this with my headers, but the figure we obtained in hp was about 199 hp or 148 kw my car is supposed to have 310hp or 228 kw at the flywheel, so if the GT has 308 at the wheels and has 330hp at the flywheel, please explain how any of this could be.
By the way this dyno is a state of the art 4wd dyno that goes to 1000 hp at the wheels.
My car which is a perfectly tuned 1984 euro s dynoed at 132 kw, at the wheels and is an auto (4 speed) I then improved this with my headers, but the figure we obtained in hp was about 199 hp or 148 kw my car is supposed to have 310hp or 228 kw at the flywheel, so if the GT has 308 at the wheels and has 330hp at the flywheel, please explain how any of this could be.
By the way this dyno is a state of the art 4wd dyno that goes to 1000 hp at the wheels.
12-01-2002, 01:45 PM
#6
928s,
Yeah, I thought that number to be very opptimistic too. I'm not saying it isn't true but different dynos give different results and they can vary greatly. The last Dyno Jet dyno run I saw on a 928 GT was 246 RWHP. I think that was low for that car but around 275 RWHP would be right on the money, for the Dyno Jet dyno the 928 GT was using, if the car were properly tuned.
The last Dyno Jet dyno run I did on my 928 before any modifications besides headers was 220 RWHP. At the time, my 928 was a 4.5L Euro engine with headers, no cats, and probably 200,000 miles. Use the dyno as a tuning tool and always run a dyno test before and after any modifications to see how well
or how poor that modification worked. 
Yeah, I thought that number to be very opptimistic too. I'm not saying it isn't true but different dynos give different results and they can vary greatly. The last Dyno Jet dyno run I saw on a 928 GT was 246 RWHP. I think that was low for that car but around 275 RWHP would be right on the money, for the Dyno Jet dyno the 928 GT was using, if the car were properly tuned.
The last Dyno Jet dyno run I did on my 928 before any modifications besides headers was 220 RWHP. At the time, my 928 was a 4.5L Euro engine with headers, no cats, and probably 200,000 miles. Use the dyno as a tuning tool and always run a dyno test before and after any modifications to see how well
or how poor that modification worked.
12-02-2002, 05:52 AM
#7
I agree Jim, use the relative figures to obtain a percentage difference. My car now dynos with the same power as a manual 996, bare in mind that my car is an auto. I think the 996 has 224 kw or 300 hp, so that seems about right to me. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
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12-02-2002, 09:23 AM
#8
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I've been to several dyno days using a dyno jet in the NorthEast. The following is corrected rear wheel horesepower.
My 90GT put down 287RWHP (stock w/RMB)
A 89GT did 289RWHP (chips)
A 91GT (strong car) did 294RWHP (stock w/RMB)
So a properly tuned GT on a dyno jet should range from about 285-300RWHP. Anything over 295RWHP is a very strong stock GT.
My hybrid EuroS track car hit 297RWHP. Hopefully a bit more is available
My 90GT put down 287RWHP (stock w/RMB)
A 89GT did 289RWHP (chips)
A 91GT (strong car) did 294RWHP (stock w/RMB)
So a properly tuned GT on a dyno jet should range from about 285-300RWHP. Anything over 295RWHP is a very strong stock GT.
My hybrid EuroS track car hit 297RWHP. Hopefully a bit more is available